The purpose of the current study was to examine the effect of 6 weeks of whole body vibration training (WBVT) on body composition, muscle activity of the gastrocnemius and vastus lateralis, gastrocnemius muscle architecture (static and dynamic) and ground reaction forces (performance jump) during the take-off phase of a countermovement jump in young healthy adult males. A total of 33 men (23.31 ± 5.62 years) were randomly assigned to a whole body vibration group (experimental group, EGWBVT: n = 17; 22.11 ± 4.97 years) or a control group (CG: n = 16; 24.5 ± 6.27 years). The total duration of the intervention phase (WBVT) was 6 weeks with a frequency of 3 sessions per week. Statistically significant differences were observed (P ≤ 0.05) between pre- and post-test in the power peak (Δ 1.91 W · kg?1; P = 0.001), take-off velocity (0.1 cm · s?1; P = 0.002) and jump height (Δ 0.4 cm; P = 0.002) for EGWBVT. There were no statistically significant differences in any of the body composition and muscle architecture variables. Moreover, no significant differences were found between EGWBVT and CG nor changes in muscle activity during take-off phase of the gastrocnemius and vastus lateralis pre- versus post-training. This study suggests that a 6-week WBVT programme with increasing intensity improves jump performance but does not alter muscle activity nor muscle architecture in healthy young men. 相似文献
It seems that dehydration may impair decision-making performance in athletes. Purpose: This study aimed to investigate the influence of dehydration on passing decision-making performance in soccer players. Method: Participants were 40 male soccer players (Mage = 22.3 ± 2.3 years) who agreed to participate in the study and were randomly assigned to the following conditions: control (CON), dehydration (DEH), and euhydration (EUH). The players played in 2 games of 90 min in duration (2 45-min halves) followed by 2 15-min halves (overtime) with and without proper hydration. The Game Performance Assessment Instrument (GPAI) was considered for the analysis of passing decision making. Results: The GPAI analysis indicated effective reduction in the decision-making index in the DEH condition compared with the EUH and CON conditions, F(2, 38) = 31.4, p < .05, ES = 0.8. Conclusions: In conclusion, dehydration may be considered a mediating factor in the passing decision-making performance of male soccer athletes. 相似文献
This study was conducted to determine the effects of inspiratory muscle training (IMT) on respiratory and peripheral muscles oxygenation during a maximal exercise tolerance test and on repeated-sprint ability (RSA) performance in professional women football players. Eighteen athletes were randomly assigned to one of the following groups: SHAM (n = 8) or IMT (n = 10). After a maximal incremental exercise test, all participants performed (on a different day) a time-to-exhaustion (Tlim) test. Peripheral and respiratory muscles oxygenation by near-infrared spectroscopy, breath-by-breath ventilatory and metabolic variables, and blood lactate concentration were measured. The RSA test was performed on a grass field. After a 6 week intervention, all athletes were reevaluated. Both groups showed increases in inspiratory muscles strength, exercise tolerance and RSA performance, however only the IMT group presented lower deoxyhemoglobin and total hemoglobin blood concentrations on intercostal muscles concomitantly to an increased oxyhemoglobin and total hemoglobin blood concentrations on vastus lateralis muscle during Tlim. In conclusion, these results may indicate the potential role of IMT to attenuate inspiratory muscles metaboreflex and consequently improve oxygen and blood supply to limb muscles during high-intensity exercise, with a potential impact on inspiratory muscle strength, exercise tolerance and sprints performance in professional women football players. 相似文献
Background:Football is the most practised sport in the world and is associated with the risk of injuries in the players.Some studies have been published that identify injury prevention programs,but there is no review of the full body of evidence on injury prevention programs for use by football coaches.The aim of this article was to carry out a systematic review of published studies on injury prevention programs for adult male footballers,identify points of common understanding and establish recommendations that should be considered in the design of injury prevention strategies.Methods:PubMed and EMBASE databases were used to identify relevant published articles using the following keywords:"soccer"AND"injury"AND"prevention".Results:A total of 2512 studies were identified initially,but only 11 studies met the inclusion criteria,and their outcomes are presented.Results revealed that injury prevention programs in football have focused on strength training,proprioceptive training,multicomponent programs(balance,core stability,and functional strength and mobility),and warm-up programs.Conclusion:Based on results from the studies analyzed,football players can lower the incidence of match and training injuries by participating in dynamic warm-up programs that include preventive exercises before games or during training sessions,and by adding strength,balance,and mobility training to the training sessions. 相似文献
Abstract The aims of the present study were (1) to analyse the physical demands of top-class referees and (2) to compare their official FIFA fitness test results with physical performance during a match. The work rate profiles of 11 international referees were assessed during 12 competitive matches at the 2003 FIFA Under-17 World Cup and then analysed using a bi-dimensional photogrammetric video analysis system based on direct lineal transformation (DLT) algorithms. In the first 15 min of matches, the referees were more active, performing more high-intensity exercise (P < 0.01) than in the first 15 min of the second half. During the second half of matches, the referees covered a shorter distance (P < 0.01), spent more time standing still (P < 0.05), and covered less ground cruising (P < 0.05), sprinting (P < 0.05), and moving backwards (P < 0.001) than in the first half. Also in the second 45 min, the distance of referees from infringements increased (P < 0.05) in the left attacking zone of the filed. There was also a decrease (P < 0.05) in performance in the period following the most high-intensity activity, compared with the mean for the 90 min. Time spent performing high-intensity activities during a match was not related to performance in the 12-min run (r2 = 0.30; P < 0.05), the 200-m sprint (r2 = 0.05; P < 0.05), or the 50-m sprint (r2 = 0.001; P < 0.05). The results of this study show that: (1) top-class referees experienced fatigue at different stages of the match, and (2) the typical field tests used by FIFA (two 50-m and 200-m sprints, followed by a 12-min run) are not correlated with match activities. 相似文献
In a knowledge-based economy, firms' technological innovations represent one of the best ways in order to survive and to achieve firm success. Nonaka and Takeuchi stated that technological innovation is close to firms' intellectual or knowledge asset management, and additional efforts are needed to understand these complex causal relationships. If we can assume that technological innovation causation rarely has a single cause, and that these causes rarely operate in isolation from each other, empirical research needs a new configurational perspective, where the integrity of firms' technological innovations as complex configurations of causal factors are preserved. This way, using a configurational approach, and primary data of 251 technology-based firms based in Spain, this paper explores firms' human, technological, and relational assets configurations and product innovations.
We examined the game dynamics in minibasketball when comparing two different forms of the 3-point line. During the first competition, participants used a 3-point line delimited by the free-throw lane, and 1,642 ball possessions were recorded. During the second competition, participants played with a 3-point line delimited by a rectangular area, and 1,669 ball possessions were recorded. Results from the Mann-Whitney U Test show that when playing with a 3-point line delimited by the free-throw lane, higher average values were achieved in terms of points scored, number of players taking part in the ball possessions, number of passes, and one-on-one situations. 相似文献
This paper studies the stabilization and passification of a class of distributed-order linear time-invariant systems, by using methods of preservation in the frequency domain. Results about preservation of stability and passivity of classical linear time-invariant systems are extended to one more general family of matrix functions. Based on these results, a new approach to the problems of stabilization and passification of distributed-order linear time-invariant systems is presented. Also a result that extends the known techniques for pole placement of classical linear time-invariant systems to the new class of distributed-order linear time-invariant systems is given. Examples are given to show the validity of theoretical results. 相似文献
The methodological characteristics of teaching in primary and secondary education make it necessary to revise the pedagogical and instructive lines with which to introduce the new Information and Communication Technologies into the school context. The construction of web pages that can be used to improve student learning is, therefore, fundamental for teachers. Their creation must be proposed, above all, from the basis of the constructivist paradigm of learning as opposed to the current behaviourist designs. General lines are established which must be convenient for the construction of web pages for these educational levels.
Les caractéristiques méthodologiques de l'enseignement à l'éducation primaire et secondaire obligent à réviser les lignes pédagogiques et instructives avec lesquelles introduire les nouvelles Technologies de l'Information et la Communication à les contextes scolaires. La construction de pages Web qui peuvent être utilisées pour améliorer l'apprentissage des élèves est, par conséquent, fondamentale pour les professeurs. Leur création doit être proposée, au‐dessus de tout, à partir de la base du paradigme constructiviste de l'apprentissage par opposition aux dessins béhavioristes courants. On établit des lignes générales qui peuvent être adéquats pour la construction de pages Web à ces niveaux pédagogiques.
Las características metodológicas de la enseñanza en educación primaria y secundaria hacen que sea necesario replantear las líneas pedagógicas e instructivas con las que introducir las nuevas Tecnologías de Información y la Comunicación en los contextos escolares. En este sentido resulta fundamental para el docente la construcción de páginas Web que puedan ser utilizadas para mejorar el aprendizaje de los alumnos. Particularmente se debe proponer su creación, ante todo, desde las bases del paradigma constructivista del aprendizaje, frente a los diseños conductistas actuales. Se establecen en esta investigación las líneas generales que deben ser convenientes para la construcción de páginas Web para estos niveles educativos.
Die methodologischen Merkmale, in Primärer und Sekundärer Ausbildung zu unterrichten, machen es notwendig, die pädagogischen und instruktiven Linien zu revidieren, mit dem die neuen Informations—und Kommunikationstechnologien in den Schulkontext einzuführen. Die Kreation von Webseiten, die benutzt werden können, um den Schülern das Lernen zu erleichtern, ist deshalb wesentlich für Lehrer. Ihre Schaffung muß vor allem von der Basis des constructivist‐Paradigmas des Lernens im Gegensatz zu den aktuellen behaviourist‐Designs vorgeschlagen werden. In dieser Untersuchung werden allgemeine Linien begründet, die für die Konstruktion der Webseiten für diese pädagogischen Niveaus günstig sein müssen. 相似文献
Today there are little more of 3 million chemist all over the world producing about 800,000 papers a year. They produce new
substances – from some hundreds in 1800 to about 20 million now – the vast majority artificial. This rate is growing quite
fast. Once the majority of chemistry teachers all over the world used textbooks as the main (sometimes the only) source of
information, we became, without wanting to... history teachers! If ‘scientific literacy’ is the aim of science lessons in school, it is much more than the literacy now developed in science
classrooms. It must include an understanding of the nature and process by which scientific activities are carried out. Recognition
of the exponentially chemistry knowledge growth and the incompleteness of the current chemistry textbooks are thus intimately
related to recognition of the need for recurrent historical teaching models. 相似文献